Observation of atomic-number-dependent hot electrons due to the resonance absorption in laser plasmas

Various hot electron temperatures depending on atomic number were measured in laser plasmas produced by a YAG laser with energy 100 mJ and pulseduration 30 ps, as was reported in our previous paper. In the present work the absorbed laser energy was evaluated as a function of the angle of incidence for both p-polarized and s-polarized beams. For carbon plasmas, it was found that the absorbed energy depends on the angle of incidence and this effect was attributed to resonance absorption. For aluminum plasmas, the resonance absorption did not occur. These results confirmed that hot electrons shown in the X-ray continuum spectrum described in the previous paper were generated by resonance absorption.